The invention generally relates to a downhole valve that has incrementally adjustable open positions and a quick close feature.
In well testing and production, it is often desirable to regulate the flow of well fluid into a tubing string. For this purpose, the tubing string may include a valve. As a more specific example, a particular type of valve is a multiple position valve, or choke. In general, the choke may have a closed setting that blocks well fluid communication through the valve, and the choke may also have multiple discrete open settings. Each open setting establishes a different cross-sectional flow area for the choke, and thus, the choke may have multiple incrementally adjustable open positions.
A conventional choke may contain a J-slot mechanism to transition the choke through its settings. With a J-slot mechanism, the choke cannot be randomly changed between settings; but rather, the choke's open and closed settings follow a predefined order, or sequence, which is established by the corresponding J-slot groove. Each setting change may be effected, for example, by cycling the pressure in a control line.
The sequence that is imposed by the J-slot mechanism may limit how quickly the choke can be closed. For example, the choke may currently be at open setting number two, out of eight open settings (as an example). To transition the choke to the closed setting from open setting number two, the choke may need to transition through all of the intervening settings (i.e., open setting number three through open setting number eight) before the closed setting is reached.